I'm not a web designer any more, but it's how I started out 7 years ago.
Any courses which colleges do are out of date, you're better off learning what you need on the internet - it's all out there for free. Start with HTML and CSS (get a good grasp of handcoding BEFORE using a wysiwyg editor)
Build up a portfolio by doing freebie sites for friends, then move onto small businesses in your local area. Most work ends up coming in through word of mouth, so as you get more work in, increase your prices.
It's not just about being a web designer - you also need to be able to sell, keep on top of your admin and motivate yourself to work (it's VERY easy to get sidetracked working from home when you don't have a boss breathing down your neck all the time).
If you want to make serious money at it, pick a niche and specialise. The market for web designers building a layout in photoshop then cropping into dreamweaver is saturated - unless you have something to stand out from the crowd, you'll be lucky to earn minumum wage.